Engine of variable stroke type

ABSTRACT

An engine of a variable stroke type may include a camshaft that a first cam and a second cam which may be adjacent to each other may be formed on the camshaft, a valve that may be disposed to be moved by the first cam or the second cam, and a tappet that may be engaged to the valve and disposed between the first and second cam and the valve to make the first cam move the valve or to make the second cam move the valve, wherein the second cam has a rotational phase difference with the first cam in a rotating direction of the camshaft.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application No. 10-2013-0122237 filed on Oct. 14, 2013, the entire contents of which is incorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to an engine of a variable stroke type that varies a cylinder from 4 to 2 stroke of a cylinder in accordance with a driving condition in such a way that fuel consumption is reduced and output is increased.

2. Description of Related Art

Generally, many arts have been introduced so as to enhance engine performance and reduce fuel consumption. One of them is a cylinder deactivation (CDA) art that operates all cylinders in a high load condition and deactivates a cylinder in a low load condition.

Further, there is an art that varies an opening timing, a closing timing, a opening duration time, and a closing duration time of an intake valve and an exhaust valve that opens an intake port and an exhaust port so as to improve engine performance and reduce fuel consumption.

Meanwhile, researches for variably controlling a stroke of an engine from 4 to 2 stroke has been being performed so as to increase performance in a high load condition and reduce fuel consumption in a low load condition for a middle size vehicle and a large size vehicle.

The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

BRIEF SUMMARY

Various aspects of the present invention are directed to providing an engine of a variable stroke type that variably controls a stroke of an engine having advantages of reducing fuel consumption in a low load condition and simultaneously increasing performance in a high load condition.

In an aspect of the present invention, an engine of a variable stroke type, may include a camshaft that a first cam and a second cam which are adjacent to each other are formed on the camshaft, a valve that is disposed to be moved by the first cam or the second cam, and a tappet that is engaged to the valve and disposed between the first and second cam and the valve to make the first cam move the valve or to make the second cam move the valve, wherein the second cam may have a rotational phase difference with the first cam in a rotating direction of the camshaft.

The number of the first cam is one in one rotational area of the camshaft, and the number of the second cam is two in one rotational area of the camshaft.

Two second cams may have a phase difference of 180 degrees.

The valve is an intake valve.

The tappet may include an inner tappet corresponding to the first cam, an outer tappet corresponding to the second cam, a middle tappet that is disposed between the inner tappet and the outer tappet to press the valve, and a latching pin that is moved by a hydraulic pressure supplied to an end thereof to latch the middle tappet with the outer tappet or to latch the middle tappet with the inner tappet.

A first lost spring that elastically biases the inner tappet toward the camshaft from the middle tappet, and a second lost spring that elastically biases the outer tappet toward the camshaft from the middle tappet.

The engine of the variable stroke type may further include a latching spring that is disposed inside the middle tappet to elastically bias the latching pin toward the outer tappet in such a way that the middle tappet is selectively latched with the outer tappet.

The hydraulic pressure is supplied to the end of the latching pin in such a way that the latching pin is pushed from a side of the outer tappet to a side of the middle tappet.

The number of the first cam is one in one rotational area of the camshaft and the number of the second cam is one in one rotational area of the camshaft.

The first cam may have a phase difference of 180 degrees with the second cam.

The valve is an exhaust valve.

The tappet may include an inner tappet that is disposed to push the valve corresponding to the first cam, an outer tappet corresponding to the second tappet, and a latching pin that is operated by a hydraulic pressure supplied to an end of the latching pin so as to latch the inner tappet with the outer tappet.

The engine of the variable stroke type may further include a lost spring that elastically biases the outer tappet from the inner tappet toward the camshaft.

The engine of the variable stroke type may further include a latching spring that is disposed inside the outer tappet elastically biases the latching pin toward the inner tappet in such a way that the inner tappet is latched with the outer tappet.

A hydraulic pressure is supplied to the end of the latching pin to push the latching pin from a side of the inner tappet to a side of the outer tappet.

In accordance with the present invention for realizing the object, a first intake cam is formed on an intake camshaft so as to realize 4 stroke cycle, two second intake cams having a phase difference of 180 degrees are formed so as to realize 2 stroke cycle, and an intake valve is lifted by the intake variable tappet corresponding to the first intake cam and the second intake cam in such a way that an engine variably realizes 4 stroke cycle or 2 stroke cycle depending on a driving condition.

Further, a first exhaust cam is formed on an exhaust camshaft for 4 stroke cycle, a second exhaust cam is formed thereon for 2 stroke cycle, and an exhaust valve is lifted by an exhaust variable tappet corresponding to the first exhaust cam and the second exhaust cam in such a way that an engine variably realizes 4 stroke or 2 stroke.

The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a valve lift device that is disposed on a normal cylinder of an engine of a variable stroke type according to an exemplary embodiment of the present invention.

FIG. 2 is a schematic perspective view of a valve lift device that is disposed on a variable cylinder of an engine of a variable stroke type according to an exemplary embodiment of the present invention.

FIG. 3 is a cross-sectional view of a tappet that is applied to a valve lift device of a normal cylinder of an engine of a variable stroke type according to an exemplary embodiment of the present invention.

FIG. 4 is a cross-sectional view of a tappet that is applied to a valve lift device of a variable cylinder of an engine of a variable stroke type according to an exemplary embodiment of the present invention.

FIG. 5 is a table showing a driving mode of an engine of a variable stroke type according to an exemplary embodiment of the present invention.

It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.

In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that the present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.

An exemplary embodiment of the present invention will hereinafter be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic perspective view of a valve lift device that is disposed on a normal cylinder of an engine of a variable stroke type according to an exemplary embodiment of the present invention.

Referring to FIG. 1, a valve lift device includes an intake valve 100, an intake tappet 110, an intake camshaft 120, an intake cam 130, an exhaust valve 102, an exhaust tappet 112, an exhaust camshaft 122, and an exhaust cam 132.

And, the intake tappet 110 and the exhaust tappet 112 don't have a lost motion function, the intake cam 130 lifts the intake valve 100 through the intake tappet 110, and the exhaust cam 132 lifts the exhaust valve 102 through the exhaust tappet 112.

FIG. 2 is a schematic perspective view of a valve lift device that is disposed on a variable cylinder of an engine of a variable stroke type according to an exemplary embodiment of the present invention.

Referring to FIG. 2, a valve lift device includes an intake valve 100, an intake variable tappet 200, an intake camshaft 120, a first intake cam 210, a second intake cam 220, an exhaust valve 102, an exhaust variable tappet 202, an exhaust camshaft 122, a first exhaust cam 212, and a second exhaust cam 222.

The first intake cam 210 and the second intake cam 220 are formed on the intake camshaft 120, and the first intake cam 210 has a phase that is different from the second intake cam 220.

More specifically, the first intake cam 210 is formed in a middle portion, the second intake cam 220 is formed at both sides of the first intake cam 210, the second intake cam 220 is formed at both sides with a phase difference of 180 degrees, and the first intake cam 210 has a phase difference of 90 degrees from the a second intake cam 220.

And, the first intake cam 210 lifts the intake valve 100 through the intake variable tappet 200, or the second intake cam 220 lifts the intake valve 100 through the intake variable tappet 200.

More specifically, a cylinder performs 4 stroke cycle while the intake valve 100 is operated by the first intake cam 210, and a cylinder performs 2 stroke cycle while the intake valve 100 is operated by the second intake cam 220.

Also, the first exhaust cam 212 and the second exhaust cam 222 are formed on the exhaust camshaft 122, and the first exhaust cam 212 and the second exhaust cam 222 have different phase.

More specifically, the first exhaust cam 212 is formed at a middle portion, the second exhaust cam 222 is formed at both sides of the first exhaust cam 212, and the first exhaust cam 212 has a phase difference of 180 degrees from the a second exhaust cam 222.

And, the first exhaust cam 212 lifts the exhaust valve 102 through the exhaust variable tappet 202 or the second exhaust cam 222 lifts the exhaust valve 102 through the exhaust variable tappet.

More specifically, while the exhaust valve 102 is operated by the first exhaust cam 212, a cylinder performs 4 stroke cycle, and when the exhaust valve 102 is operated by the second exhaust cam 222, a cylinder performs 2 stroke cycle.

FIG. 3 is a cross-sectional view of a tappet that is applied to a valve lift device of a normal cylinder of an engine of a variable stroke type according to an exemplary embodiment of the present invention.

Referring to FIG. 3, an exhaust variable tappet 202 includes an inner tappet 300, a latching pin 310, a pin cap 320, a latching spring 330, a hydraulic chamber 340, an outer tappet 350, and a lost spring 360.

An inner tappet 300 is disposed on a middle portion corresponding to the first exhaust cam 212, and an outer tappet 350 is disposed on an outer side of the inner tappet 300 corresponding to the second exhaust cam 222.

The inner tappet 300 is disposed to press the exhaust valve 102, a latching pin 310 and a latching spring 330 are disposed in a hydraulic chamber 340 that is formed inside the outer tappet 350, and the hydraulic chamber 340 is sealed by the pin cap 320.

Here, the latching spring 330 elastically supports the latching pin 310 in such a way that the outer tappet 350 is latched with the inner tappet 300. Meanwhile, in a case in which hydraulic pressure is supplied to the hydraulic chamber 340, the latching pin 310 compresses the latching spring 330 in such a way that the latching of the inner tappet 300 and the outer tappet 360 is released.

If the latching of the inner tappet 300 and the outer tappet 360 is released, the outer tappet 360 performs a lost motion through the lost spring 360.

FIG. 4 is a cross-sectional view of a tappet that is applied to a valve lift device of a variable cylinder of an engine of a variable stroke type according to an exemplary embodiment of the present invention.

Referring to FIG. 4, an intake variable tappet 200 includes an inner tappet 410, a middle tappet 420, an outer tappet 430, a latching pin 440, a stopper 450, a hydraulic chamber 460, a first lost spring 470, a second lost spring 480, and a latching spring 400.

A latching spring 400 is disposed inside the inner tappet 410, and the latching pin 440 is disposed at both sides of the latching spring 400. If the hydraulic pressure is not supplied, the latching pin 440 is moved backward to latch the outer tappet 430 with the middle tappet 420, and if the hydraulic pressure is supplied, the latching pin 440 is moved forward to latch the middle tappet 420 with the inner tappet 410.

In a condition in which hydraulic pressure is not supplied, the stopper 450 prevents the backward movement of the latching pin 440 in such a way the latching condition of the middle tappet 420 and the outer tappet 430 is maintained.

As shown, a central portion of the middle tappet 420 is opened upward, the first lost spring 470 is disposed therein, and the first lost spring 470 elastically supports the inner tappet 410 upward.

In a condition in which the latching pin 440 latches the middle tappet 420 with the outer tappet 430, the inner tappet 410 performs a lost motion through the first lost spring 470. And, in a condition in which the latching pin 440 latches the inner tappet 410 with the middle tappet 420, the outer tappet 430 performs a lost motion through the second lost spring 480.

FIG. 5 is a table showing a driving mode of an engine of a variable stroke type according to an exemplary embodiment of the present invention.

Referring to FIG. 5, an engine includes 4 stroke normal cylinder and variable stroke cylinder (VSC, 2 stroke <->4 stroke).

And, in a first mode, hydraulic pressure is supplied to the intake variable tappet 200 and the exhaust variable tappet 202 that are mounted in the variable stroke cylinder, and in a second mode, hydraulic pressure is not supplied to the intake variable tappet 200 and the exhaust variable tappet 202 that are mounted on the variable stroke cylinder.

Accordingly, in the first mode, the latching pin 440 of an intake variable tappet 200 of the variable stroke cylinder latches the inner tappet 410 and the middle tappet 420 through the hydraulic pressure and the outer tappet 430 performs a lost motion by a second intake cam 220. And, the inner tappet 410 and the middle tappet 420 operate the intake valve 100 through the first intake cam 210.

In the first mode, the latching pin 440 of the exhaust variable tappet 202 of the variable stroke cylinder release the latching condition of the inner tappet 300 and the outer tappet 350 through hydraulic pressure, and the outer tappet 350 performs a lost motion through a second exhaust cam 222. And, the first exhaust cam 212 performs the exhaust valve 102 through the inner tappet 300.

Further, in the second mode, the latching pin 440 of the intake variable tappet 200 of the variable stroke cylinder latches the middle tappet 420 with the outer tappet 430 through hydraulic pressure not supplied, and the inner tappet 410 performs a lost motion through a first intake cam 210. And, the second intake cam 220 operates the intake valve 100 through the outer tappet 430 and the middle tappet 420.

In the second mode, the latching pin 330 of the exhaust variable tappet 202 of the variable stroke cylinder latches the inner tappet 300 and the outer tappet 350 through hydraulic pressure not supplied. And, the exhaust valve 102 is operated by the first exhaust cam 212 and the second exhaust cam 222.

As described above, a first intake cam 210 is formed on an intake camshaft 120 so as to realize 4 stroke cycle, two second intake cams 220 having a phase difference of 180 degrees are formed so as to realize 2 stroke cycle, and an intake valve 100 is lifted by the intake variable tappet 200 corresponding to the first intake cam 210 and the second intake cam 220 in such a way that an engine variably realizes 4 stroke cycle or 2 stroke cycle depending on a driving condition.

Also, a first exhaust cam 212 is formed on an exhaust camshaft 122 for 4 stroke cycle, a second exhaust cam 222 is formed thereon for 2 stroke cycle, and an exhaust valve 102 is lifted by an exhaust variable tappet 202 corresponding to the first exhaust cam 212 and the second exhaust cam 222 in such a way that an engine variably realizes 4 stroke or 2 stroke.

For convenience in explanation and accurate definition in the appended claims, the terms “upper”, “lower”, “inner” and “outer” are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents. 

What is claimed is:
 1. An engine of a variable stroke type, comprising: a camshaft that a first cam and a second cam which are adjacent to each other are formed on the camshaft; a valve that is disposed to be moved by the first cam or the second cam; and a tappet that is engaged to the valve and disposed between the first and second cam and the valve to make the first cam move the valve or to make the second cam move the valve; wherein the second cam has a rotational phase difference with the first cam in a rotating direction of the camshaft.
 2. The engine of the variable stroke type of claim 1, wherein the number of the first cam is one in one rotational area of the camshaft, and the number of the second cam is two in one rotational area of the camshaft.
 3. The engine of the variable stroke type of claim 2, wherein two second cams have a phase difference of 180 degrees.
 4. The engine of the variable stroke type of claim 3, wherein the valve is an intake valve.
 5. The engine of the variable stroke type of claim 3, wherein the tappet includes: an inner tappet corresponding to the first cam; an outer tappet corresponding to the second cam; a middle tappet that is disposed between the inner tappet and the outer tappet to press the valve; and a latching pin that is moved by a hydraulic pressure supplied to an end thereof to latch the middle tappet with the outer tappet or to latch the middle tappet with the inner tappet.
 6. The engine of the variable stroke type of claim 5, further comprising: a first lost spring that elastically biases the inner tappet toward the camshaft from the middle tappet; and a second lost spring that elastically biases the outer tappet toward the camshaft from the middle tappet.
 7. The engine of the variable stroke type of claim 5, further comprising a latching spring that is disposed inside the middle tappet to elastically bias the latching pin toward the outer tappet in such a way that the middle tappet is selectively latched with the outer tappet.
 8. The engine of the variable stroke type of claim 7, wherein the hydraulic pressure is supplied to the end of the latching pin in such a way that the latching pin is pushed from a side of the outer tappet to a side of the middle tappet.
 9. The engine of the variable stroke type of claim 1, wherein the number of the first cam is one in one rotational area of the camshaft and the number of the second cam is one in one rotational area of the camshaft.
 10. The engine of the variable stroke type of claim 9, wherein the first cam has a phase difference of 180 degrees with the second cam.
 11. The engine of the variable stroke type of claim 9, wherein the valve is an exhaust valve.
 12. The engine of the variable stroke type of claim 9, wherein the tappet includes: an inner tappet that is disposed to push the valve corresponding to the first cam; an outer tappet corresponding to the second tappet; and a latching pin that is operated by a hydraulic pressure supplied to an end of the latching pin so as to latch the inner tappet with the outer tappet.
 13. The engine of the variable stroke type of claim 12, further comprising a lost spring that elastically biases the outer tappet from the inner tappet toward the camshaft.
 14. The engine of the variable stroke type of claim 12, further comprising a latching spring that is disposed inside the outer tappet elastically biases the latching pin toward the inner tappet in such a way that the inner tappet is latched with the outer tappet.
 15. The engine of the variable stroke type of claim 12, wherein a hydraulic pressure is supplied to the end of the latching pin to push the latching pin from a side of the inner tappet to a side of the outer tappet. 